1. Field of the Invention
The present invention relates to a sound collector which collects sound using a microphone placed inside a hood.
2. Description of the Related Art
Conventionally, a hammering tone test system is known which hits a surface to be tested using a striking tool such as a hammer, collects sound (hereinafter referred to as “hammering tone”) generated by the hammering using a microphone and analyzes the sound to detect defects such as cavities in the test object (e.g., see Non-Patent Document 1).
In the hammering tone test system described in the Non-Patent Document 1, the sound generated in the hammering test is collected by a sound collector provided with a microphone placed in the center and a stethoscope type sound collection hood for shutting off surrounding sound.
Here, since impulse sound produced by a hammering test, etc., is not continuous sound, it is necessary to collect an acoustic signal in a short time and accurately.
However, in the case of an acoustic diagnosis of impulse sound, sound is reflected (including diffuse reflection) and reaches the sound collector instantaneously, and therefore it is sometimes difficult to realize accurate acoustic diagnosis.
Therefore, it is possible to adopt a sound collector already proposed by the present inventor (see Patent Document 1) which places an acoustical absorbent at the back in the collection hood and absorbs a sound wave produced from a test object and reflected on an inner wall surface of the sound collection hood to thereby prevent interference among sound waves.
FIG. 1 is a cross-sectional view of the sound collector having already proposed by the present inventor.
FIG. 1 shows a sound collector 100 provided with an acoustical absorbent 130 inside a sound collection hood and the acoustical absorbent 130 of this sound collector 100 is placed in the sound collection hood facing an opening surface 114 of the sound collection hood.
(Non-Patent Document 1)
“Testing Technology”, July 2002 issue, pp 41-45 (technological topics/architecture, civil engineering) (Patent Document 1)
Japanese Patent Publication No. 3223237